diff --git a/CMakeLists.txt b/CMakeLists.txt
index c2fdce8..56977c8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,7 +10,7 @@ endif()
 if(CMAKE_CXX_COMPILER_ID STREQUAL "Intel")
   message("setting intel true")
   set(IntelComp true )
-elseif(CMAKE_CXX_COMPILER_ID MATCHES "GNU*")
+elseif(CMAKE_CXX_COMPILER_ID MATCHES "GNU*" OR CMAKE_CXX_COMPILER_ID MATCHES "Clang*")
   set(GNUComp true )
 elseif(CMAKE_CXX_COMPILER_ID MATCHES "pgc*")
   set(PGIComp true )
@@ -31,16 +31,16 @@ find_package( ZLIB )
 if( (BUILD_RELEASE) OR (BUILD_PRODUCTION) )
   if(IntelComp)
     message("setting intel flags")
-    set(CMAKE_C_FLAGS "-O3 -c -O3 -axCore-AVX2 -g -DUNDERSCORE" CACHE INTERNAL "" )
+    set(CMAKE_C_FLAGS "-c -O3 -axCore-AVX2 -g -DUNDERSCORE" CACHE INTERNAL "" )
     set(CMAKE_Fortran_d_FLAGS "-c -O3 -axCore-AVX2 -g -free " CACHE INTERNAL "" )
   elseif(GNUComp)
-    set(CMAKE_C_FLAGS "-O3 -ggdb -Wall " CACHE INTERNAL "" )
-    set(CMAKE_Fortran_d_FLAGS "-ffree-form -fdefault-integer-8 -fdefault-real-8 -O3 -funroll-loops -ggdb -Wall " CACHE INTERNAL "" )
+    set(CMAKE_C_FLAGS "-c -O3 -ggdb -Wall -g -DUNDERSCORE" CACHE INTERNAL "" )
+    set(CMAKE_Fortran_d_FLAGS "-c -O3 -g -ffree-form -funroll-loops -ggdb -Wall " CACHE INTERNAL "" )
   elseif(PGIComp)
     set(CMAKE_C_FLAGS "-g -fast -DUNDERSCORE -DLINUX " CACHE INTERNAL "" )
-    set(CMAKE_Fortran_d_FLAGS "-i8 -r8 -g -fast " CACHE INTERNAL "" )
+    set(CMAKE_Fortran_d_FLAGS "-g -fast " CACHE INTERNAL "" )
   else()
-    message("unkown compiler!")
+    message("unknown compiler!")
     exit()
   endif()
 endif()